Differential pressure control



`Maly 24, 193,48. M. F. BOOTH DIFFERENTIAL PRESSURE ONTROL Filed Dec. 25, 1931 I lllllllllllllll lllll I Illlrllllllllll lllll l Il@ Patented May-|24, 193s UNITED STA-TES Z2 Claims.

This invention relates to a differential pressure control, and has to do particularly with a novel control for unloading a condenser and predetermining the effective head pressure in a refriger- 5 ating system.

The main object ofthe present invention is the `elimination of the high Iside or low side oat in refrigerating systems of the ooded type and substituting therefor a control for unloading the.

condenser into the lowsideat a predetermined pressure which is directly proportioned to the temperature existing around the condnser or nthe control Aunit as the case may be. hnother feature resulting from the mbodiment l5 ofthe present invention is the elimination of the excessive head pressure in starting up a warm*r machine. ff

Still further features reside in the maintenance of a constant level in the cooling unit:A the optional elimination of a receiver; the use of a' relatively small amount of liquid in the condenser. Other'novel` features reside in the combination of a novel oil return system foruse `with my high side control and other details of construction and operation' as will be more clearly brought out in .the specication and claims. r

In the drawing:

Fig. 1 is a diagrammaticillustration 'showing the manner of connectingmy control unit in a standard refrigerating system. f

Fig. 2 is an enlarged sectional view of my con- `trol unit. D C Fig. 3 is a view similar to'Fig. 2, but illustratcing a slightly modified form of the unit wherein liquid is the motion transmitting means instead of a ro d as in Fig'. 2. f u

Fig'. 4 is an enlarged view similar to Figs. v2 and -3 but showing a modified manner of transmitting the movement of one bellows member to the K 40 other.

Fig. '5 is an enlarged fragmentaryjview illustrating the preferred\,manner of controlling the oil `return from a lowside equippedwlth my tnovel control unit. f

In the preferred'form my control unit consists of a housing 2 enclosing a bellows member 3. The end of the housing is provided with a port g leading from thehigh side and an outlet port leading to the lowside. A needle valve t controls the admission o f a-refrigerant .fromwithin the bellows member to the lowslde outlet.

A tube 'I forms theconnecting means between the housing 2 and a remotely positioned housing 8 and this'housing 0 encloses a second bellows member sowhich is in direct communicationwith (ci. ca -a) a conduitl or bulb- I0 ofrelatively large surface area. A rod I I connectsthe two bellows members and also controls the actuation of the valve 6. In preparing the refrigerating systemfor operation, the air is preferably exhausted therefrom 5 and the required amount of refrigerant placed in the cooling unit. Upon opening up the 'serviceV valve in. the-usual manner, the machine being warm, the ycompressor will start in response to whatever control might be used. rIt will be under- 10 stood here that the operation of the compressor may be regulated by a pressure or temperature control in the ordinary manner.

If BO: is the refrigerant used in the refrigerating system I prefer to use SO2 in the second bel- 15 lows member, but I may use methyl chloride in the bellows member 9 and in the tube I 0. The amount of pressure of methyl chloride is substantially identical numerically'with the surrounding room temperature Fahrenheit and will increase 2o or decrease accordingly, as the room .temperature is varied. The-pressure of SO2 runs about ten pounds below the existing room temperature. In any case it will thus be seen that under ordinaryconditions. the needle valve 8 will remain closed. 25 A light spring I2 can be used to insure aiposltive" closing action over and above the pressure diiferential in the two bellows members. 'I'he spring l I2 acts against a suitable pin carried by the rod Il andl operating in a slot provided in .the conduit 30 .1. vIn the event that the needle should leak because` of dirtv or other sediment, it will be obvious that the high and low side will tend to equalize v.

with the result that the pressure in the bellows member 9 will be relatively greater than the pres- 35 sure in the bellows member 3. with the result f that the .top bellows member will tend to push clear away the dirt or sediment.

In starting up a warm machine. with the atmosphere around the condenser at, say, the needle valve 6 will remain closed until'the pressure of the SO: in the bellows member 3 rises to 45 a point slightly aboveseventy pounds and the L small amount of refrigeranti has been condensed and collected in the bottom ofthe condenser. When the needle valve opens a small amount of this refrigerant will be discharged into the low- 50 side, decreasing the pressure and causing the needle valve to again close. It will b e obvious that there will be a.l uttering action of the -control as` long as the motor continues in operation.

A receiver is not necessary in the system and but 55 I a very small amount of liquid accumulates in the condenser. The condenser C is preferably provided with fins or other means to provide a large surface area with theresult that the pressure in the high side will rapidly drop back towards absolute pressure` after the motor has stopped and the needle valve closed.

The level or amount of liquid in tl're lowside will remain substantially constant for the reason that when a certain portion of the refrigerant is removed from the lowsideby operation of the compressor, a pressure is immediately built up in the control, anda small amount of the liquid accumula-ted in the condenser, and receiver if used, is' transferred to the lowside. The'only time that any change takes place in the lowside is when the Icompressor is operatingand this combined withx',d

the iiuttering action will tend to the maintenance of a constant level or amount of refrigerant in the cooling unit.

The large surface area of the conduitor bulb l0 insures `the maintenance of a pressure within the bellows 9 which is highly sensitive to any change in temperature of the atmosphere surrounding the condenser. It will be understood that any gas may be used in the bellows 9, the

pressure of which 'is responsive to changes in temperature and, if desired, the `same refrigerant used in the refrigerating system`\ may be used in the bellows 9. In this case I prefer to increase the diameter of the` bellows member 9 as compared to the diameter of the bellows ,member 3 to obtain the desired dierential pressure.

In Fig. 2 I have shown a modified form of the invention wherein the fiat diaphragm i3 is substituted for the bellows member 9 and a tube lll lled with a liquid serves as the power transmitting means instead of the rod il.

In Fig. 3 I have illustrated a further modification wherein a fiexible cable l5 surrounded by a reinforcing tube serves as the connecting means between the two bellows members.

In Fig. 4 I have illustrated a further modication of my invention wherein the complete regulating device is formed as a single compact unit. In this structure the lowside connection is at i6 and the high side connection at il and a single sylphon i8 serves as a separating means between the two liquids or gases. A needle valve i9 preferably has a loose fit with the side w-alls 20 or may be a square needle so that the refrigerant in the system fills the interior of the bellows i8 as at 2l. The refrigerant 22 on the outside of the bellows may be the same as the refrigerant in the system but this' is not necessary as heretofore explained in connection with Fig. l. The operation of the structure shown in Fig. 4 is ysubstantially the same as the operation of the structure shown in Fig. l except that in most cases it will be impossible to locate'the unit as shown in Fig. 4 adjacent the condenser. The spring 23 holds the needle i9 in closed position until the pressure in they high side more than equals the pressure of the liquid 22 plus the pressure of the spring 23,' in which case the needle opens allowing the refrigerant from the high side I'l to ow to the lowside as at I6 until 'the pressure in the high side is not great enough to hold the needle open.

In Fig. 5 I have diagrammatically illustrated the preferred location of my regulating unit as at A in a refrigerating system wherein B is the compressor, C is the condenser, and D the coolingunit. The location of a portion of the control inside or outside of the box will depend largely upon whether the type of unit shown in Fig. 1 or Fig. 4 is used.

What I claim is:

1. In a refrigerating system of the type having a condenser, compressor and lowside. a control unit having valve means for connecting and unloading liquid refrigerant from the high side into the lowside, thermostatically controlled means operatively positioned adjacent the eondenser and connected to and normally tending to close said valve means whereby the pressure in the high side necessary to open the valve will .vary according to the temperature existing around the condenser, and spring means positioned and arranged to resist or mist the operation of the thermostatic controlled means in the operation of the valve.

2. In a mechanical refrigerating system of theA flooded type, an unloading valve positioned between the condenser and evaporator, said valve including a'valve stem for controlling the iiow of liquid from the condenser to the evaporator, a bellows member surrounding the valve stem and in continuous communication with and filled by refrigerant liquid from` the condenser, thermostatic means including a housing surrounding said bellows member and filled -with temperature responsiveliquid, a conduit con-` nected to said housing and filled with liquid, said conduit being exposed to atmospheric air, said temperature responsive liquid surrounding the bellows member and the effective exposed surface of said bellows member being such that said valve stern will normally remain closed to shut off the flow' of liquid to the evaporator until the`development of the required amount of pressure in the high side of the system.

3. A control valve for regulating the unloading of liquid in the condenser into the lowside of a refrigerating system as liquid, comprising a bellows enclosed and normally closed Valve member subject to high lside pressure, a second bellows member having temperature responsive means positioned adjacent to but spaced from the circulating refrigerant in the condenser and containing a medium adapted to expand or contract with changes in atmospheric temperature,

said bellows members being connected together whereby the high side pressure necessary to open the valve in the first' bellows member will be directly predetermined by the temperature exist- .tween the condenser and evaporator, said valve including 'a valve stem for controlling the flow of liquid from the condenser to the evaporator, a bellows member operatively connected to the 1 valve stem and in continuous communication with and actuated by refrigerant liquid from the condenser, thermostatic means positioned to be affected by. the temperature of the air and the temperature of the condenser when running, said thermostatic means being operatively connected to said valve stem, the head pressure in the liquid coming from the high pressure side of the system being the sole means for opening said valve.

5. In a mechanical refrigerating system of the flooded type, an unloading valve positioned be tween the condenser and evaporator, said valve including a valve stem for controlling the flow of liquid from the condenser to the evaporator, a bellows member operatively connected to the valve stem and in continuous communication surface of said bellows member, a needle valve with and adapted to be operated by refrigerant liquid from the condenser, thermostatic' means positioned to be ail'ected by the temperature of atmospheric air and the temperature of the liquid passing through the condenser and including refrigerant liquid having a portion of its body positioned adjacent said condenser and a portion enclosed in a chamber whereby to be normally operative against and tending to'close said valve stem, nthe vapor pressure of said refrigerant forming a part of the thermostatic means varying in accordance with the temperature of the atmospheric air andv the temperature of the liquid passing through the condenser whereby the point at which said valve stem may be opened by the pressure of the liquid from the high side will 'vary according to said temperatures.

6. In a refrigerating system of the type having a condenser, compressor and iowsidet a control unit interposed between the condenser and lowside and having valve means forconnecting and unloadingliquid refrigerant from the high side into the 'lowside, a bellows member confined within a housing operatively connected to the valve means, said bellows member being in communication with and actuatedby liquid from the condenser, and means tending to always move the valve towards closed position including atmospheric temperature responsive means ior exerting a closing pressure on the valve means proportionate to atmospheric temperature con-V ditions.

'7. In a refrigerating system of the type having a condenser. compressor and lowside, a` control unitinterposed between'the condenser and lowside and having valve means for connecting and unloading liquid refrigerant from the high side into the lowside, a bellows member conned within a housing operatively connected to the valve means, said bellows member being in communication with and actuated by` liquid from the condenser, 'and means tending to alwaysmove the valve towards closed position including atf mospherictemperature responsive means for eX- erting a closing pressure on the valve means proportionate to atmospheric temperature condi-A tions, said second named means also including resilient means positioned to resist or assist the operation` of the temperature responsive means in the operation ofsaid valve means.

. 8. In areirigerating system of the type having a. condenser, compressor and lowside, a control unit interposed between the condenser and lowside and having valve means for connecting and unloading liquid refrigerant fromi the high side into the lowside, a bellows member conined within a housing operatively connected to the valve means, said bellows member being in communication with and actuated by liquid from the condenser, and means tending lto always move the valve towards closed position including atmospheric temperature responsive means forexerting a closing pressure on the Valve means and through the bellows member proportionate stant body ofirefrlgerant liquid against the other' 'volatility against the bellows, Said valve body being provided with a portion adjacent the bottom thereof and between the bellows and the seat and apertured to receive the needle valve member and provide a passageway through which the refrigerant passes to permit the same to contact with one side of said bellows member and to pass through said seat.

10. A pressure valve for a refrigerating sys-l tem including an evaporator, a compressor, and a condenser, comprising `a valve body i'ormed with a refrigerant inlet port, a metallic bellows member in said valve body, a body oi liquid in said valve body contacting with one surface of said bellows member'and of diiferent volatility than the refrigerant, said inlet port being incomniunication with the condenser to vsupply a constant body of refrigerant liquid against the other surface oi' said bellows member, a needle vglve projecting from said bellows member, a seat in said valve body :i: st which said needle valve member is adapted to be pr bythe expansive action of the liquid of diderent volatility against the bellows, s aid valve being provided with a poi-tion adiacent'one end thereof and between the bellows and the seat and apertured to receive the needle valve member and provide a se, ageway throlmh which the refrigerant pes to permit the same to contact with one side ci said bellows member and to `pass through said seat, anda spring within said valve 'body positioned to resist or assist the operation of said bellows member in controlling the operation of said valve.

v 1i. A pressure valve for a refrigerating system including an evaporator, a compressor, and a condenser, comprising a valve b formed with a refrigerant inlet port, a metallic bellows member in saidyalve body, a .body of liquid in said valve bodycontacting with one surface of said bellows member and of diderent volatility than the refrigerant, said inlet port being inl communication with the condenser to supply a constant body of refrigerant liquid against the other sur- Y a portion adjacent one end thereof and between the bellows and the seat and apertured to receive the needle valve member and provide a passage- -way through which the refrigerant passes to permit the same to contact with'one side oi' said bellows memberiand to pass through said seat, said liquid oi' diterent volatility being so positioned as to lbe aiected by the temperature conditions oi the atmosphere.

, 12. A pressure valve for a refrigerating system including an evaporator. a compressor, and a condenser, comprising a valve Vbody formed with a refrigerant inlet port, a metallic bellows member in said valve body, a body of liquid in said valve bodv contacting with one surface o! said bellows member and ot different volatility than the refrigerant, said inlet port being in communication with the condenser to supplyv a con stent body oi'refrigerant liquid against the other surface of said bellows member, a needle valve projecting downwardly from said bellowsmem# ber, a seat in said v alve body againstwhich said needle valve member is adapted to be pressed by r the expansive action of the liquid of dierent volatility against the bellows, said valve body being provided with a portion adjacent the bot-.

tom thereof and between the bellows and the `seat and apertured to'receive the needle valve member and provide a passageway through which the refrigerant passes to permit the same to contact with one side of said bellows member and to pass through said seat, and a conduit leading from said valve body and-having a portion thereof positioned adjacent the condenser, s aid conduit being filled with and in communication with said liquid of different volatility.

13. A differential pressure control for regulating the delivery of liquid from the condenser to the lowside of a. refrigerating system during operation of the compressor comprising valve means for normally separating the liquid in the con.--

denser and lowside, atmospheric temperature responsive means positioned adjacent to but spaced from the circulating refrigerant in the condenser and tending to move the valve towards closed position, means subject to the pressure existing in the high side tending to counteract said first named means, and opening said valve only upon accumulation of suiicient pressure in the high side to overcome the pressure exerted by said rst named means.

14. A control valve for regulating the unloading of the liquid in the condenser into the lowside of a refrigerating system, comprising a bellows en-4 closed valve member, said bellows being connected to the high side of the system, a second bellows member connected to temperature responsive means positioned adjacent to but spaced from the circulating refrigerant in the condenser and containing a medium adapted to expand or contract with vchange in atmospheric temperature, said bellows members being connected `to gether whereby the high side pressure necessary to open the valve'in the first bellows member will be directly predetermined by the temperature existing around the second bellows member, and adjustable resilient means normally tendingl to close the valve member. l

15. 'A refrigerating system comprising, in combination, a high pressure side, a low pressure side, means responsive to the pressure of the refrigerant in the high pressure side for controllingthe admission of refrigerant to said low' pressure side, and means vresponsive to changes in temperature of the ambient air which cooled.

the high pressure side for' controlling the operation gf said controlling means.

16. Refrigerating apparatus comprising, in

Acombinatioman evaporator, means for circulating refrigerant through the evaporator including a condenser, means responsive to the pressure of the refrigerant in said condenser for controlling the flow of refrigerant to the evaporator, and means arranged in heat receiving relation to but spaced from said condenser for controlling the operation of said second named means.

aliases Vl'l'. Refrigerating apparatus comprising, in

combination, an evaporator, means for circulate ingrefrigerant through the evaporator including heat dissi-pating means arranged to increase in temperature when. refrigerant is circulated, said heat dissipating means being cooled by a medium owing thereover, means responsive to the pressure of the refrigerant insaid circulating means for controlling the flow of refrigerant to the evaporator, and means arranged in heat receiving relation to but spaced from said heat dissipating means and subjected to the temperature of the cooling medium for varying the operation of said controlling means.

18. Refrigerating apparatus comprising, inA

combination, an evaporator, 'means for circulating refrigerant through said evaporator including a condenser, means responsive to the pressure of the refrigerant in said condenser f or controlling the iiow of refrigerant to the evaporator, and means con/taining a refrigerant whose pressure is higher than the refrigerant in said condenser at the same temperatures and being arranged in heat receiving relation to said condenser for controlling the operation of said second named means.

19. A refrigerating system comprising a high pressure side, a low pressure side, an expansion valve operable to pass liquid refrigerant only from the high pressure side to the low pressure Vside during one period of operation and to pass both liquid and gaseous refrigerant to the low pressure side during another period of operation and means for actuating said expansion valve.

20. A refrigerating system comprising a condensing element, an evaporating element, expansion vvalve means operable to pass only liquid refrigerant from the condensing element to the evaporating element during normal cycling operation `of Ithe condensing element, and to pass 'liquid and gaseous refrigerant to the evaporathaving high and low pressure portions which w consists in supplying refrigerant from the high to the low pressure portion under the inuence of the pressure exerted in the high pressure por- `Vtion, circulating a cooling medium for cooling the high pressure portion, and modifying the passage of refrigerant to the low pressure portion in response to temperature changes of the cooling medium which is atvariance with respect to the pressure temperatures in the'high pressure portion.

d MORRIS F. BOOTH. v 

